Ruthenium complexes with tridentate PNX (X = O, S) donor ligands

Abstract

The ligands, PhPNXMe (1), PhPNXPh (2), and PhPNSMe (3), (PhPNX = 2-Ph₂P-C₆H₄CHNC₆H₄X-2; X = O, S) have been prepared. A range of new ruthenium complexes were synthesised using these and related ligands, namely: [{RuCl(PhPNO)}₂Cl] (4), [Ru(PhPNO)₂] (5), [RuCl(PhPNXR)(PPh₃)]BPh₄ [X = O, R = Me (6); X = O, R = Ph (7); X = S, R = Me (8)], [{RuCl(PhPNX′R)}₂Cl]X [X′ = O, R = Me, X = Cl⁻ (9); X′ = S, R = Me, X = BPh₄⁻ or PF₆⁻ (10)], and [RuCl(PhPNO-η⁶C₆H₅)]BPh₄ (11). The catalytic activity of these complexes with respect to the hydrosilyation of acetophenone and the hydrogenation of styrene has been investigated, giving an insight into the requirements for an active complex in these reactions.